Asking patients to monitor their own medications can be fatal, as exemplified by the recent death of actor Heath Ledger. In the first large-scale study of home medication consumption, sociologists at the University of California, San Diego have found a 3,196 percent increase in fatal domestic medication errors involving alcohol and/or street drugs.

Their study examines nearly 50 million U.S. death certificates from 1983 to 2004, and focuses on a subset of 200,000 deaths from medication errors. The study appears in the July 28 issue of the Archives of Internal Medicine, an official journal of the American Medical Association.

“The decades-long shift in the location of medication consumption from clinical to domestic settings,” the authors say, “is linked to a dramatic increase in fatal medication errors.”

“Increasingly,” says principal author David P. Phillips, professor of sociology at UC San Diego, “people take their medications at home, away from hospitals and clinics. But most studies of fatal medication errors have focused on those clinical settings. We wanted to know three things: how many of these fatal errors happen at home; how many involve alcohol and/or street drugs; and are these numbers going up?”

Phillips and his co-authors Gwendolyn E.C. Barker and Megan M. Eguchi, all at UC San Diego, examined trends in four types of fatal medication errors. They note that the increase in fatal errors varies by astonishing amounts based on where the errors occur and the particular combinations of drugs.

In addition to possible changes in policy and clinical practice, Phillips says, “it also seems advisable to expand research on medication errors. Much of this research has focused on elderly patients and clinical settings. The present findings suggest that more research should be devoted to middle-aged patients and domestic settings.”

The study was supported in part by a grant from the Marian E. Smith Foundation.

Ledger, the actor, was cast as the Joker in the current hit movie “The Dark Knight,” shortly before dying, on January 22, 2008, from an accidental prescription-drug overdose at age 28.